Radar sensors are increasingly used for safety-relevant assistance functions in motor vehicles, for example, for an adaptive cruise control and/or for collision warning or collision avoidance systems. Since malfunctions of the radar sensor may have serious consequences in these applications, it is essential to closely monitor the operability of the radar sensor. For this reason, monitoring routines are provided in known control units, with which it is possible to constantly or periodically monitor essential functions of the radar sensor and the control unit during operation, such that the control unit has a certain self-diagnostic capability.
Prior to the initial operation of the radar sensor, the monitoring functions should also be subjected to a functional test in order to ensure that the monitoring functions correctly detect the error conditions that they are to monitor, and that the control unit reacts appropriately to the detected errors, for example, with a partial or complete automatic shutdown, output of error signals, and the like.
Typically, near-series radar sensors and associated control units are used for the functional test of the monitoring functions, and errors are injected into the system via external modifications. The software of the control unit must detect these errors and initiate corresponding measures. This error reaction is then observed and evaluated during the test.
In the electronic control units for radar sensors, integrated high-frequency components, so-called MMICs (Monolithic Microwave Integrated Circuit) are increasingly used. Such MMICs may contain the entire high-frequency part for multiple transmission and receiver channels of the radar sensor, and additionally contain an integrated controller (microcontroller) for controlling the individual components of the MMICs and for controlling the data traffic using a higher-level external controller. While the highly integrated structure has numerous advantages, it causes difficulties if internal error conditions need to be generated in the MMICs for the functional test.
While it is possible, in principle, with the aid of specialized software to generate such error conditions, the functional tests must be carried out in close to real-world conditions, in particular using the released series software, in which certain modifications, which would support carrying out the functional tests, are not permissible.
In known methods for carrying out the functional tests, signal lines and/or programming lines on the circuit board of the MMIC are contacted with needle adapters in order to falsify output signals in a targeted manner or to manipulate data packets in a targeted manner.
However, it is disadvantageous in these methods that the radar sensor must be disassembled and opened so that access to the lines is obtained. This change of the surroundings may cause corruption of error reactions which do not occur in actual operation. In addition, the disassembly and re-assembly of the radar sensor is time-consuming and labor-intensive, and therefore costly.